The purpose of this project is to develop a single preparation with which to take a more holistic approach to the nervous system than has previously been possible, that is, to examine not only the structure and operation of a well defined neural network underlying specific behaviors, but also the genetics and development of the system. Orthopteran insects have been selected, first because their nervous system displays many of the features which have made various invertebrates appealing to neruobiologists, and secondly because they are amenable to developmental and genetic investigations. To date, it has been possible to (a) characterize physiologically and anatomically neural systems containing individually identified cells which generate particular behavior patterns, (b) to investigate the structural and functional differentiation of elements of the system and to observe how the network becomes operative during post-embryonic development, and (c) to examine genetic control of the system through hybridization and through selection of single gene mutants for circuit elements. The coming year will be devoted (a) to quantification of the behaviroal deficit follwoing complete loss of a class of sensory neurons in a mutant, to ultrastructural confirmation of the extent of loss, and to examination of adjustments of post-synaptic cells to the loss of input, and (b) to detailed investigation of the anatomical and physiological development of identified neurons involved in certain adult behaviors.